.gamma.-vinyl-.gamma.-butyrolactone is a compound which has been reported to be useful for conversion to sorbic acids; see U.S. Pat. Nos. 4,022,822 and 4,158,741. .gamma.-vinyl-.gamma.-butyrolactone has been reported to be prepared in a reaction of butadiene and acetic acid with trivalent manganese at elevated temperature; see U.S. Pat. No 4,175,089. In a copending application Ser. No. 222,200 filed of even date herewith, applicants have claimed a process for preparing acyloxyhexenoic acids by reaction of butadiene and acetic acid with metal oxidants.